The present invention generally relates to the field of fogging devices. In particular, the invention is directed toward fogging devices utilizing the pulse-jet, or resonant intermittent combustion, principle.
Fogging devices, used to generate an insecticide fog, for example, and utilizing the pulse-jet or resonant intermittent combustion principle, are well known in the prior art. Examples of such devices are disclosed in U.S. Pat. No. 3,993,582 to Curtis, U.S. Pat. No. 4,030,695 to Curtis, and U.S. Pat. No. 4,343,719 to Stevens et al. Each of these patents discloses a fogging apparatus utilizing a resonant, intermittent combustion device, a fuel supply, a formulation supply, a formulation control device, and a starting device. In such prior art devices, the resonant intermittent combustion device is shut off by way of a valve located in the carburetor.
Fogging devices disclosed in U.S. Pat. No. 4,811,901 to Stevens et al. (“the '901 patent”) and U.S. Pat. No. 4,934,601 to Stevens et al. (“the '601 patent”), both of which are hereby incorporated by reference into the present application, provide an improved starting system for the resonant intermittent combustion device, an improved combustion device shut off system, and an improved formulation control device over previous fogging devices. These fogging devices utilize ignition systems that generally require at least 12 volts DC for supplying power to ignite the fogging device. Additionally, these ignition systems are typically grounded via a single grounding means. However, there are potential safety concerns that exist with having only a single grounding means.
Accordingly, a need has arisen for improving the design of these fogging devices by implementing a secondary grounding means. In particular, there is a need for a pulse fog generator with an ignition system operating from a low voltage power source and at least one additional grounding means, which in combination, would reduce the overall weight of the machine, lower the cost of the machine, and eliminate wasted energy required for starting the machine.